The mission of this Core is to provide histologic and hematopoietic research support services to UCSF Cancer Center investigators studying the pathogenesis and treatment of organ and hematologic malignancies in mouse models of human cancer. This facility provides services for members in the Mouse Models of Human Cancer Program and investigators in other programs. Histology services include processing, embedding, and histologic sectioning of murine tissues in paraffin, frozen, and plastic blocks (with re-embedding of tissue as necessary) and routine histochemical staining (hematoxylin and eosin, other histochemical stains). The Core also provides expertise in murine hematology. Complete blood counts are provided for investigators, including preparation of blood smears for analysis of white blood cell, red blood cell, and platelet morphology. In addition, the Core assists investigators analyzing hematopoietic tissues, including cytologic and histologic preparations of bone marrow, spleen, and lymph nodes. The Core will develop a network or mouse pathologists from different institutions and make this network available to members a shared resource in the future.